Marine-derived uronic acid-containing polysaccharides: Structures, sources, production, and nutritional functions

Uronic acid-containing polysaccharides (UACPs) are a class of polysaccharides containing at least one type of uronic acid (UA) and have been widely used in medical and food industries because of their unique physicochemical properties and bioactivities. Marine organisms, a major source of natural products, provide abundant UACPs with novel structures. Exploring the biological activities of marine-derived UACPs and their molecular mechanisms, especially for those with different monosaccharide composition and molecular weights (MWs), is critical for elucidating the structure-function relationships and promoting the application of marine-derived UACPs in different fields. This review comprehensively covers the current knowledge of the potential sources and health benefits of marine-derived UACPs with different monosaccharide compositions and MWs. Moreover, the main methods for the production of marine-derived UACPs and their derivatives are also summarized in this review. This paper reviews recent research on marine-derived UACPs and provides future research directions for this field. Marine-derived UACPs exert various nutritional functions, displaying antioxidant, immunomodulatory, hypolipidemic, hypoglycemic, and regulating gut microbiota activities. Moreover, the monosaccharide composition, MW, and presence of unsaturated non-reducing ends are key factors affecting the nutritional function of marine-derived UACPs. In the future, more in vivo tests are needed to confirm the nutritional properties of marine-derived UACPs and their derivatives with different compositions, such as those containing different UAs and varying sulfate contents. Moreover, the molecular mechanisms underlying the properties of marine-derived UACPs and their structure-function relationships deserve further attention.